PA62. Kayfun V4 Peek Sub Ohm Replacement Center Post The 4s kit for the Kayfun V4 atomizer including increased flow center post with 2.7 mm internal bore to allow greatly increased air flow to the coil. Kit also includes a PEEK insulator for high temperature builds. Kit Contains: - Replacement center post - PEEK positive block insulator Price: $2.00 Unit: Each Quantity: